net/tls/tls_device_fallback.c

   1 /* Copyright (c) 2018, Mellanox Technologies All rights reserved.
   2  *
   3  * This software is available to you under a choice of one of two
   4  * licenses.  You may choose to be licensed under the terms of the GNU
   5  * General Public License (GPL) Version 2, available from the file
   6  * COPYING in the main directory of this source tree, or the
   7  * OpenIB.org BSD license below:
   8  *
   9  *     Redistribution and use in source and binary forms, with or
  10  *     without modification, are permitted provided that the following
  11  *     conditions are met:
  12  *
  13  *      - Redistributions of source code must retain the above
  14  *        copyright notice, this list of conditions and the following
  15  *        disclaimer.
  16  *
  17  *      - Redistributions in binary form must reproduce the above
  18  *        copyright notice, this list of conditions and the following
  19  *        disclaimer in the documentation and/or other materials
  20  *        provided with the distribution.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  26  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  27  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  28  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  29  * SOFTWARE.
  30  */
  31
  32 #include <net/tls.h>
  33 #include <crypto/aead.h>
  34 #include <crypto/scatterwalk.h>
  35 #include <net/ip6_checksum.h>
  36
  37 #include "tls.h"
  38
  39 static void chain_to_walk(struct scatterlist *sg, struct scatter_walk *walk)
  40 {
  41         struct scatterlist *src = walk->sg;
  42         int diff = walk->offset - src->offset;
  43
  44         sg_set_page(sg, sg_page(src),
  45                     src->length - diff, walk->offset);
  46
  47         scatterwalk_crypto_chain(sg, sg_next(src), 2);
  48 }
  49
  50 static int tls_enc_record(struct aead_request *aead_req,
  51                           struct crypto_aead *aead, char *aad,
  52                           char *iv, __be64 rcd_sn,
  53                           struct scatter_walk *in,
  54                           struct scatter_walk *out, int *in_len,
  55                           struct tls_prot_info *prot)
  56 {
  57         unsigned char buf[TLS_HEADER_SIZE + TLS_CIPHER_AES_GCM_128_IV_SIZE];
  58         struct scatterlist sg_in[3];
  59         struct scatterlist sg_out[3];
  60         u16 len;
  61         int rc;
  62
  63         len = min_t(int, *in_len, ARRAY_SIZE(buf));
  64
  65         scatterwalk_copychunks(buf, in, len, 0);
  66         scatterwalk_copychunks(buf, out, len, 1);
  67
  68         *in_len -= len;
  69         if (!*in_len)
  70                 return 0;
  71
  72         scatterwalk_pagedone(in, 0, 1);
  73         scatterwalk_pagedone(out, 1, 1);
  74
  75         len = buf[4] | (buf[3] << 8);
  76         len -= TLS_CIPHER_AES_GCM_128_IV_SIZE;
  77
  78         tls_make_aad(aad, len - TLS_CIPHER_AES_GCM_128_TAG_SIZE,
  79                 (char *)&rcd_sn, buf[0], prot);
  80
  81         memcpy(iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, buf + TLS_HEADER_SIZE,
  82                TLS_CIPHER_AES_GCM_128_IV_SIZE);
  83
  84         sg_init_table(sg_in, ARRAY_SIZE(sg_in));
  85         sg_init_table(sg_out, ARRAY_SIZE(sg_out));
  86         sg_set_buf(sg_in, aad, TLS_AAD_SPACE_SIZE);
  87         sg_set_buf(sg_out, aad, TLS_AAD_SPACE_SIZE);
  88         chain_to_walk(sg_in + 1, in);
  89         chain_to_walk(sg_out + 1, out);
  90
  91         *in_len -= len;
  92         if (*in_len < 0) {
  93                 *in_len += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
  94                 /* the input buffer doesn't contain the entire record.
  95                  * trim len accordingly. The resulting authentication tag
  96                  * will contain garbage, but we don't care, so we won't
  97                  * include any of it in the output skb
  98                  * Note that we assume the output buffer length
  99                  * is larger then input buffer length + tag size
 100                  */
 101                 if (*in_len < 0)
 102                         len += *in_len;
 103
 104                 *in_len = 0;
 105         }
 106
 107         if (*in_len) {
 108                 scatterwalk_copychunks(NULL, in, len, 2);
 109                 scatterwalk_pagedone(in, 0, 1);
 110                 scatterwalk_copychunks(NULL, out, len, 2);
 111                 scatterwalk_pagedone(out, 1, 1);
 112         }
 113
 114         len -= TLS_CIPHER_AES_GCM_128_TAG_SIZE;
 115         aead_request_set_crypt(aead_req, sg_in, sg_out, len, iv);
 116
 117         rc = crypto_aead_encrypt(aead_req);
 118
 119         return rc;
 120 }
 121
 122 static void tls_init_aead_request(struct aead_request *aead_req,
 123                                   struct crypto_aead *aead)
 124 {
 125         aead_request_set_tfm(aead_req, aead);
 126         aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
 127 }
 128
 129 static struct aead_request *tls_alloc_aead_request(struct crypto_aead *aead,
 130                                                    gfp_t flags)
 131 {
 132         unsigned int req_size = sizeof(struct aead_request) +
 133                 crypto_aead_reqsize(aead);
 134         struct aead_request *aead_req;
 135
 136         aead_req = kzalloc(req_size, flags);
 137         if (aead_req)
 138                 tls_init_aead_request(aead_req, aead);
 139         return aead_req;
 140 }
 141
 142 static int tls_enc_records(struct aead_request *aead_req,
 143                            struct crypto_aead *aead, struct scatterlist *sg_in,
 144                            struct scatterlist *sg_out, char *aad, char *iv,
 145                            u64 rcd_sn, int len, struct tls_prot_info *prot)
 146 {
 147         struct scatter_walk out, in;
 148         int rc;
 149
 150         scatterwalk_start(&in, sg_in);
 151         scatterwalk_start(&out, sg_out);
 152
 153         do {
 154                 rc = tls_enc_record(aead_req, aead, aad, iv,
 155                                     cpu_to_be64(rcd_sn), &in, &out, &len, prot);
 156                 rcd_sn++;
 157
 158         } while (rc == 0 && len);
 159
 160         scatterwalk_done(&in, 0, 0);
 161         scatterwalk_done(&out, 1, 0);
 162
 163         return rc;
 164 }
 165
 166 /* Can't use icsk->icsk_af_ops->send_check here because the ip addresses
 167  * might have been changed by NAT.
 168  */
 169 static void update_chksum(struct sk_buff *skb, int headln)
 170 {
 171         struct tcphdr *th = tcp_hdr(skb);
 172         int datalen = skb->len - headln;
 173         const struct ipv6hdr *ipv6h;
 174         const struct iphdr *iph;
 175
 176         /* We only changed the payload so if we are using partial we don't
 177          * need to update anything.
 178          */
 179         if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
 180                 return;
 181
 182         skb->ip_summed = CHECKSUM_PARTIAL;
 183         skb->csum_start = skb_transport_header(skb) - skb->head;
 184         skb->csum_offset = offsetof(struct tcphdr, check);
 185
 186         if (skb->sk->sk_family == AF_INET6) {
 187                 ipv6h = ipv6_hdr(skb);
 188                 th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
 189                                              datalen, IPPROTO_TCP, 0);
 190         } else {
 191                 iph = ip_hdr(skb);
 192                 th->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
 193                                                IPPROTO_TCP, 0);
 194         }
 195 }
 196
 197 static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
 198 {
 199         struct sock *sk = skb->sk;
 200         int delta;
 201
 202         skb_copy_header(nskb, skb);
 203
 204         skb_put(nskb, skb->len);
 205         memcpy(nskb->data, skb->data, headln);
 206
 207         nskb->destructor = skb->destructor;
 208         nskb->sk = sk;
 209         skb->destructor = NULL;
 210         skb->sk = NULL;
 211
 212         update_chksum(nskb, headln);
 213
 214         /* sock_efree means skb must gone through skb_orphan_partial() */
 215         if (nskb->destructor == sock_efree)
 216                 return;
 217
 218         delta = nskb->truesize - skb->truesize;
 219         if (likely(delta < 0))
 220                 WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
 221         else if (delta)
 222                 refcount_add(delta, &sk->sk_wmem_alloc);
 223 }
 224
 225 /* This function may be called after the user socket is already
 226  * closed so make sure we don't use anything freed during
 227  * tls_sk_proto_close here
 228  */
 229
 230 static int fill_sg_in(struct scatterlist *sg_in,
 231                       struct sk_buff *skb,
 232                       struct tls_offload_context_tx *ctx,
 233                       u64 *rcd_sn,
 234                       s32 *sync_size,
 235                       int *resync_sgs)
 236 {
 237         int tcp_payload_offset = skb_tcp_all_headers(skb);
 238         int payload_len = skb->len - tcp_payload_offset;
 239         u32 tcp_seq = ntohl(tcp_hdr(skb)->seq);
 240         struct tls_record_info *record;
 241         unsigned long flags;
 242         int remaining;
 243         int i;
 244
 245         spin_lock_irqsave(&ctx->lock, flags);
 246         record = tls_get_record(ctx, tcp_seq, rcd_sn);
 247         if (!record) {
 248                 spin_unlock_irqrestore(&ctx->lock, flags);
 249                 return -EINVAL;
 250         }
 251
 252         *sync_size = tcp_seq - tls_record_start_seq(record);
 253         if (*sync_size < 0) {
 254                 int is_start_marker = tls_record_is_start_marker(record);
 255
 256                 spin_unlock_irqrestore(&ctx->lock, flags);
 257                 /* This should only occur if the relevant record was
 258                  * already acked. In that case it should be ok
 259                  * to drop the packet and avoid retransmission.
 260                  *
 261                  * There is a corner case where the packet contains
 262                  * both an acked and a non-acked record.
 263                  * We currently don't handle that case and rely
 264                  * on TCP to retranmit a packet that doesn't contain
 265                  * already acked payload.
 266                  */
 267                 if (!is_start_marker)
 268                         *sync_size = 0;
 269                 return -EINVAL;
 270         }
 271
 272         remaining = *sync_size;
 273         for (i = 0; remaining > 0; i++) {
 274                 skb_frag_t *frag = &record->frags[i];
 275
 276                 __skb_frag_ref(frag);
 277                 sg_set_page(sg_in + i, skb_frag_page(frag),
 278                             skb_frag_size(frag), skb_frag_off(frag));
 279
 280                 remaining -= skb_frag_size(frag);
 281
 282                 if (remaining < 0)
 283                         sg_in[i].length += remaining;
 284         }
 285         *resync_sgs = i;
 286
 287         spin_unlock_irqrestore(&ctx->lock, flags);
 288         if (skb_to_sgvec(skb, &sg_in[i], tcp_payload_offset, payload_len) < 0)
 289                 return -EINVAL;
 290
 291         return 0;
 292 }
 293
 294 static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
 295                         struct tls_context *tls_ctx,
 296                         struct sk_buff *nskb,
 297                         int tcp_payload_offset,
 298                         int payload_len,
 299                         int sync_size,
 300                         void *dummy_buf)
 301 {
 302         sg_set_buf(&sg_out[0], dummy_buf, sync_size);
 303         sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
 304         /* Add room for authentication tag produced by crypto */
 305         dummy_buf += sync_size;
 306         sg_set_buf(&sg_out[2], dummy_buf, TLS_CIPHER_AES_GCM_128_TAG_SIZE);
 307 }
 308
 309 static struct sk_buff *tls_enc_skb(struct tls_context *tls_ctx,
 310                                    struct scatterlist sg_out[3],
 311                                    struct scatterlist *sg_in,
 312                                    struct sk_buff *skb,
 313                                    s32 sync_size, u64 rcd_sn)
 314 {
 315         struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
 316         int tcp_payload_offset = skb_tcp_all_headers(skb);
 317         int payload_len = skb->len - tcp_payload_offset;
 318         void *buf, *iv, *aad, *dummy_buf;
 319         struct aead_request *aead_req;
 320         struct sk_buff *nskb = NULL;
 321         int buf_len;
 322
 323         aead_req = tls_alloc_aead_request(ctx->aead_send, GFP_ATOMIC);
 324         if (!aead_req)
 325                 return NULL;
 326
 327         buf_len = TLS_CIPHER_AES_GCM_128_SALT_SIZE +
 328                   TLS_CIPHER_AES_GCM_128_IV_SIZE +
 329                   TLS_AAD_SPACE_SIZE +
 330                   sync_size +
 331                   TLS_CIPHER_AES_GCM_128_TAG_SIZE;
 332         buf = kmalloc(buf_len, GFP_ATOMIC);
 333         if (!buf)
 334                 goto free_req;
 335
 336         iv = buf;
 337         memcpy(iv, tls_ctx->crypto_send.aes_gcm_128.salt,
 338                TLS_CIPHER_AES_GCM_128_SALT_SIZE);
 339         aad = buf + TLS_CIPHER_AES_GCM_128_SALT_SIZE +
 340               TLS_CIPHER_AES_GCM_128_IV_SIZE;
 341         dummy_buf = aad + TLS_AAD_SPACE_SIZE;
 342
 343         nskb = alloc_skb(skb_headroom(skb) + skb->len, GFP_ATOMIC);
 344         if (!nskb)
 345                 goto free_buf;
 346
 347         skb_reserve(nskb, skb_headroom(skb));
 348
 349         fill_sg_out(sg_out, buf, tls_ctx, nskb, tcp_payload_offset,
 350                     payload_len, sync_size, dummy_buf);
 351
 352         if (tls_enc_records(aead_req, ctx->aead_send, sg_in, sg_out, aad, iv,
 353                             rcd_sn, sync_size + payload_len,
 354                             &tls_ctx->prot_info) < 0)
 355                 goto free_nskb;
 356
 357         complete_skb(nskb, skb, tcp_payload_offset);
 358
 359         /* validate_xmit_skb_list assumes that if the skb wasn't segmented
 360          * nskb->prev will point to the skb itself
 361          */
 362         nskb->prev = nskb;
 363
 364 free_buf:
 365         kfree(buf);
 366 free_req:
 367         kfree(aead_req);
 368         return nskb;
 369 free_nskb:
 370         kfree_skb(nskb);
 371         nskb = NULL;
 372         goto free_buf;
 373 }
 374
 375 static struct sk_buff *tls_sw_fallback(struct sock *sk, struct sk_buff *skb)
 376 {
 377         int tcp_payload_offset = skb_tcp_all_headers(skb);
 378         struct tls_context *tls_ctx = tls_get_ctx(sk);
 379         struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
 380         int payload_len = skb->len - tcp_payload_offset;
 381         struct scatterlist *sg_in, sg_out[3];
 382         struct sk_buff *nskb = NULL;
 383         int sg_in_max_elements;
 384         int resync_sgs = 0;
 385         s32 sync_size = 0;
 386         u64 rcd_sn;
 387
 388         /* worst case is:
 389          * MAX_SKB_FRAGS in tls_record_info
 390          * MAX_SKB_FRAGS + 1 in SKB head and frags.
 391          */
 392         sg_in_max_elements = 2 * MAX_SKB_FRAGS + 1;
 393
 394         if (!payload_len)
 395                 return skb;
 396
 397         sg_in = kmalloc_array(sg_in_max_elements, sizeof(*sg_in), GFP_ATOMIC);
 398         if (!sg_in)
 399                 goto free_orig;
 400
 401         sg_init_table(sg_in, sg_in_max_elements);
 402         sg_init_table(sg_out, ARRAY_SIZE(sg_out));
 403
 404         if (fill_sg_in(sg_in, skb, ctx, &rcd_sn, &sync_size, &resync_sgs)) {
 405                 /* bypass packets before kernel TLS socket option was set */
 406                 if (sync_size < 0 && payload_len <= -sync_size)
 407                         nskb = skb_get(skb);
 408                 goto put_sg;
 409         }
 410
 411         nskb = tls_enc_skb(tls_ctx, sg_out, sg_in, skb, sync_size, rcd_sn);
 412
 413 put_sg:
 414         while (resync_sgs)
 415                 put_page(sg_page(&sg_in[--resync_sgs]));
 416         kfree(sg_in);
 417 free_orig:
 418         if (nskb)
 419                 consume_skb(skb);
 420         else
 421                 kfree_skb(skb);
 422         return nskb;
 423 }
 424
 425 struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
 426                                       struct net_device *dev,
 427                                       struct sk_buff *skb)
 428 {
 429         if (dev == tls_get_ctx(sk)->netdev || netif_is_bond_master(dev))
 430                 return skb;
 431
 432         return tls_sw_fallback(sk, skb);
 433 }
 434 EXPORT_SYMBOL_GPL(tls_validate_xmit_skb);
 435
 436 struct sk_buff *tls_validate_xmit_skb_sw(struct sock *sk,
 437                                          struct net_device *dev,
 438                                          struct sk_buff *skb)
 439 {
 440         return tls_sw_fallback(sk, skb);
 441 }
 442
 443 struct sk_buff *tls_encrypt_skb(struct sk_buff *skb)
 444 {
 445         return tls_sw_fallback(skb->sk, skb);
 446 }
 447 EXPORT_SYMBOL_GPL(tls_encrypt_skb);
 448
 449 int tls_sw_fallback_init(struct sock *sk,
 450                          struct tls_offload_context_tx *offload_ctx,
 451                          struct tls_crypto_info *crypto_info)
 452 {
 453         const u8 *key;
 454         int rc;
 455
 456         offload_ctx->aead_send =
 457             crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
 458         if (IS_ERR(offload_ctx->aead_send)) {
 459                 rc = PTR_ERR(offload_ctx->aead_send);
 460                 pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc);
 461                 offload_ctx->aead_send = NULL;
 462                 goto err_out;
 463         }
 464
 465         key = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->key;
 466
 467         rc = crypto_aead_setkey(offload_ctx->aead_send, key,
 468                                 TLS_CIPHER_AES_GCM_128_KEY_SIZE);
 469         if (rc)
 470                 goto free_aead;
 471
 472         rc = crypto_aead_setauthsize(offload_ctx->aead_send,
 473                                      TLS_CIPHER_AES_GCM_128_TAG_SIZE);
 474         if (rc)
 475                 goto free_aead;
 476
 477         return 0;
 478 free_aead:
 479         crypto_free_aead(offload_ctx->aead_send);
 480 err_out:
 481         return rc;
 482 }